The present invention relates to a technique for improving the compatibility in the memory card, specifically to a technique effective in use for securing the compatibility in the card memory conforming to the HS-MMC (High Speed-Multimedia Card) mode.
The market has accepted the memory cards such as the multimedia card (registered trademark) standardized by the MMCA (Multimedia Card Association) being a standardization association, and the SD (Secure Digital) card (registered trademark) standardized by the SDA (SD card Association), as one of the external storage media for personal computers and multi-function terminals, etc. These memory cards are used for recording static images by a digital camera, recording communication data by a mobile telephone, and recording reproduced music by a portable music player, etc.
Many host computers including personal computers and multi-function terminals and so forth conform to both of the multimedia card and the SD card. Although the multimedia card and the SD card are different in the number of the external terminals (7 terminals in the multimedia card/9 terminals in the SD card), the multimedia card is thinner than the SD card, and the external terminal position thereof is compatible with that of the SD card. Therefore, the multimedia card can be used on the host computer that permits using the SD card.
In the normal mode of the multimedia card, as for the data output timing, the setup time/hold time of the data output is stipulated to the rise edge of the clock signal, as shown in FIG. 25 (refer to the standard specification by the MMCA for the details of the multimedia card).
On the other hand, in the case of the SD card, the timing of the data output is stipulated by the delay time from the fall edge of the clock signal, as shown in FIG., 26 (refer to the standard specification by the SDA for the details of the SD card).
In the case of using the multimedia card on the host computer conforming to the SD card, the data output timing is different; accordingly, the data differs from that of the SD card, and there arises an impossibility of the compatibility with each other.
Thus, some multimedia cards secure the compatibility with the host conforming to the SD card, by taking the timing being in time for the setup time and executing the data output at the fall edge of the clock signal.